It is conventional to desalt or dehydrate oil-continuous emulsions by introducing such emulsions directly into an electric treating field of sufficient intensity to coalesce the suspended droplets of the dispersed phase into masses of sufficient size to gravitate from the oil. The dispersed phase of such emulsions is composed of a material, usually aqueous, that is sufficiently immiscible with the oil to produce an internal or dispersed phase. Initially, the dispersed droplets are of such small size or are so stabilized that they will not readily gravitate from the oil phase. However, the electric field coalesces such dispersed droplets, and it is found that the resulting coalesced masses gravitate rapidly from the oil, usually in the same container as that in which electric treatment takes place. In a desalting operation, a quantity of water may be mixed with the incoming crude oil in a valve or other mixer, all as well known, so that a more complete removal of salt from the oil may be accomplished. Typical of such prior art dehydrator/desalters are those described in the following U.S. Pat. Nos.: 1,838,922 2,513,386 2,855,360 3,141,000 3,531,393 2,033,446 2,527,690 2,880,158 3,207,686 3,577,336 2,041,954 2,543,996 2,892,768 3,250,695 3,649,516 2,072,888 2,557,847 2,894,895 3,458,429 3,672,127 2,443,646 2,848,412 2,963,414 3,592,756 3,736,245; and German Pat. No. 1,014,076 (Helmut Stock; Aug. 22, 1957).
U.S. Pat. Nos. 4,149,958 and 4,182,672 to Robert B. Martin disclose apparatus and processes for desalting or dehydrating emulsions of the type above described, wherein the apparatus has a plurality of electrified coalescing stages in a single vessel, wherein the stages are hydraulically substantially independent and adapted for parallel or series stage operations. The expression "electrified" denotes the presence of an electric field, as above described. In one embodiment shown by Martin, two or more electrified stages, each separately energized, are operated in parallel to proportionately increase vessel throughput capacity. In another embodiment, especially designed for desalting, series operation is employed, wherein each successive stage receives the product of the preceding stage as feed, with fresh and/or recycled water being added.
The embodiments specifically illustrated and described in the Martin patents incorporate centrally positioned emulsion inlet distributors between horizontally disposed planar permeable electrodes in vertically spaced relationship. Among the distributors there disclosed are those in the form of pipes or box-like ducts provided with rows of orifices along their lengths.
In the concurrently filed application of James R. Robinson, Ser. No. 187,282, filed Sept. 15, 1980, improved apparatus of this type, wherein the emulsion being treated is introduced at one wall of the vessel and caused to flow to the opposite wall between horizontal planar permeable electrodes, is disclosed and claimed.
It is known to employ a distributor in the form of an inverted trough, with orifices along the sides of the trough. A distributor of this type, sometimes referred to as a "pan-type" distributor, is shown in U.S. Pat. No. 3,458,429 to Federick D. Watson and Weldon D. Mayse and is used for feeding incoming liquid into a container of liquid for uniform upward flow of the incoming liguid through the liquid in the container. A variation of such a distributor is shown in U.S. Pat. No. 3,649,516 to Ernest A. Cole, Jr., Frederick D. Watson, and Weldon D. Mayse. A distributor employing a baffle having orifices therein is shown in U.S. Pat. No. 3,672,127, to Weldon D. Mayse and Frederick D. Watson.
It is an object of this invention to provide an improved and simplified fluid inlet distributor for feeding an imcoming fluid in substantially uniform horizontal flow in a fluid treating vessel.
It is a further object of this invention to provide such a fluid inlet distributor well suited for use in electric treating apparatus for dehydrating and/or desalting emulsions such as crude petroleum oil.
It is a still further object of this invention to provide such a distributor particularly adapted for use in plural stage electric treating apparatus of this type.